HAPPY B'DAY 8052.COM!!!! WISHING YOU ALL THE VERY BEST!!!
Thank you all .. Thank you so very much for all the information that you have provided and I Appreciate that.
Secondly .. I am still stuck.. and i need help
There are wide gaps that I need to fill . I hope no one minds my amateurish , not so intelligent:-) questions!!!

Here's what's happening,
2 items from the menu are displayed on the lcd, the patron scrolls thru the items list , ( slave will display the items and know where the cursor is ie the corresponding row of that page).

Let's say a customer liked the 2nd item on the 4th page( if that can be said) he hits enter, the patron gets a message "would you like to confirm the order? - ( slave writes to LCD) - customer hits EN enter- 2 things happen:
1.Lcd displays the list again.
2.order is confirmed ( every item corresponding to a row is say given a code - that is copied to

the acc. and is ready to be xfered .. copied to sbuf )
and now I am in trouble!!!
Now , there are 2 possibilities of working with this part,
ie 1.The master "polls" every slave device to see ,checks TI, if there is anything that needs to

be xfered, and if the polled device wished to xfer info it will do so immediately.... that means

the master is active at all times, ...

or 2. i could use interrupts .. raise INT0/1 on slave, send it on bus to master µc, which when

received by the master , sends an acknowledgement and asks to send data, and is ready to receive

the data and process it.

I really don't know what's the best solution here....

Let's look at the next issue.
1.When slave wishes to send the so called data to the master , we intend to use RS 485 USING

SN75176b. P3.1 (pin 11) of slave is connected to pin 4, and P3.0 (pin 10) is connected to pin 1

of SN75176B (I'll call it RS 485) RE(rs pin 2) to p 3.2( µc 12), and DE( rs pin 3) to p 3.3 (µc

13)
Lets say i wish to send some bits from the slave to the master .
ie . µc needs to make pin 4 (d) high and pin 3(DE) high as well. the truth table provided by the

manufacturer indicates o/p A would be high and o/p B would be low ......
on the master side vid>.2 v to be able to recive ... ahem .. well i really really don't know

how that translates to any communication ... !!!!

I know I am missing a lot here... I'd appreciate if you can help me understand this RS485!!
URGHHHHHHH......